They reached a peak in their 2-0 home win over Real Madrid at the end of November and, although they were comfortable winners over City the following Sunday, there has been a sense since of a side, if not quite clinging on to the mountain top, then at the very least not striding quite so confidently along the ridge.
It may be a modern phenomenon that the side top of the table have lost only one of 26 games, and that the side in second have lost two, but after the years of champions habitually racking up 90 points and more, the general fallibility has been refreshing.
Quite aside from the various problems with injury and ageing players and the failure of recruitment that led them to sign four players in January, what was striking on Wednesday was their passivity in losing to Real Madrid, the acquiescence in defeat.
The mechanism is supremely sophisticated, perhaps better honed than any coach has made their teams before, but that requires players to sublimate themselves to the system and that means when the mechanism glitches, there is an absence of personal fight, of initiative, of the capacity to grab a game and drag it back.
There is the short-term problem of whether Liverpool can hold on – and an eight-point lead is extremely healthy, even having played a game more, particularly given Arsenal, their only realistic challenger, have lost their forward line to hamstring injuries.
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